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Module 2 – Lesson 3

Lesson 3: Solar Prominences and Sunspots 

Overview

The first lesson on the Sun starts with the qualitative comparisons that students practiced in Module 1. Here we compare the size of the Sun to the Earth, locate sunspots on the Sun, and determine its rotation period.  We also investigate solar prominences and compare them to the size of the Earth. Students will refine their measurements using Earth-scaled beads on a string as a ruler. 

Learning Outcomes 

  • Quantitatively compare the Earth and Sun in size. 
  • Explain what a solar prominence is and quantitatively compare the size of the Earth to the size of a solar prominence.
  • Describe how solar magnetic fields and coronal loops are produced.
  • Describe what a sunspot is. 
  • Given a sunspot shown at different times, calculate the Sun’s rotational period at that solar latitude and compare it to the value given in the text, pg. 35 of Touch the Sun. 

Materials needed 

  • Touch the Sun Braille book by Noreen Grice (if available)
  • Different size balls, from 1 mm to 300 mm 
  • 3 mm “Earth beads” 
  • Cafeteria trays or aluminum bins to keep all beads and small materials.
  • 12 inch diameter Styrofoam Sun ball with attached sunspots (washers, beads, or indentations).
  • Flexible wire loops to attach to the sunspots on the Sun balls.
  • Earth measurement ruler: 3 mm Earth beads attached to a stiff wire.

The “Sun” is represented by a 12-inch Styrofoam ball mounted on a regular cold-drink cup so that students can tell which way is “up.” The sunspots are represented by circles cut out of magnetic sheets and glued onto the foam. By using paper clips or other wire, students can tell the magnetic characteristics of the “sunspots.” The looping wire from two of the sunspots represents a large prominence. If a smaller foam ball is used for the Sun, then the Earth measuring beads should be proportionally smaller as well to maintain the correct relative measurements.

Large styrofoam ball having black tacks for pairs of sunspots and wire loops connecting each pair.

Figure 2.3.1. A 12-inch Styrofoam ball is converted into our sun with sunspots and prominences. The solar equator and poles are marked but not visible here.

Pre-assessment Questions and Discussion

Q. Which is the closest star to Earth?
A. The Sun

Q. What makes our star, the Sun, special and important to life on Earth?
A. Almost all life is dependent on the Sun for energy, warmth; plants use sunlight to grow.

Q. How long does it take light to leave the Sun to reach Earth?
A. About 8 minutes.

Q. What is your guess as to how the size of the Sun compares to the Earth?
A. Interesting answers may be expected.

Text

Students should read pages 3-5, 19-21, 23-29, 31-33, 35-37, and 39-41 of Touch the Sun, with the reading broken up into logical, reasonable blocks of time. See follow-up questions for assessing learning and guiding discussions. 

  1. Earth and Sun Size Comparison: pp. 3-5. Tactile picture on pg. 5 gives the comparison with a line-up of Earth’s across the Sun’s equator.
    1. 1. How different are the sizes of the Earth and the Sun? 
    2. 2. Were you surprised at what you found?
  2. Comparison of a prominence and our Earth: pp. 19-21. Tactile picture on pg. 21 demonstrates a comparison of the size of a typical solar prominence with the size of our Earth.
    1. 1. What is a solar prominence? How is it created?
    2. 2. How does the size of the Earth compare to the size of a solar prominence? Were you surprised at this?
  3. The Sun with Magnetic Field Lines and The Sun as Seen by the TRACE Satellite: pp. 23-29. Tactile picture on pg. 25 shows how the Sun would look if we could “see” magnetic field lines. Tactile picture on pg. 29 shows coronal loops as seen by NASA’s TRACE solar telescope. 
    1. 1. What produces the solar magnetic fields? 
    2. 2. How are coronal loops produced?
  4. The Sun with Sunspots: pp. 31-33 and Sunspots in Motion Over Time: pp. 35-37. Tactile picture on pg. 33 shows an image of the Sun with sunspots. 
    1. 1. Describe what a sunspot is, including its temperature, how it is formed, what it looks like. 
    2. 2. Tactile picture on pg. 37 shows sunspot motion over time. 
    3. 3. Comment on what you discovered about the Sun’s rotational period.
  5. Size Comparison of Earth and a Sunspot: pp. 39 – 41. Tactile picture on pg. 41 gives comparison of Earth size to size of a sunspot. 
    1. 1. Quantitatively compare the size of the Earth to the size of other solar features.

Follow up Questions on Reading

Included with sectional reading above. 

Reinforcing Hands-On Activities

Exploration and Measurement: 

Students locate the sunspots on the Styrofoam sun by touch and by using a paper clip to detect them. If properly placed, some students may discover their distribution both above and below the Sun’s equator. 

Using the sun ball, students attach flexible wire loops to sunspots on the surface to create solar prominences and coronal loops.

Students are given an Earth measurement ruler consisting of 3 mm “Earth beads” (each bead representing an increment of Earth diameter) attached to a stiff wire. This ruler measures the sizes of various solar features in terms of the Earth’s diameter.

Group discussions should follow each part of the lesson.  Suggested topics include the detection of the sunspots, ease in building the solar prominences, expression of the sizes of solar prominences, and overall impressions of the activity of the Sun.

Summary and Post-Assessment Questions

    1. About 110 earths would fit across the diameter of the Sun. What does that comparison mean to you?
    2. Part of the Sun’s activity includes the huge arcs of plasma and gas called prominences. How does the size of the Earth compare to those?
    3. The Sun has a magnetic field that extends well out into the solar system. Does the Earth have a magnetic field? Do we have objects here on Earth that can create magnetic fields?
    4. Explain what sunspots and prominences are. What do the magnetic fields of the Sun have to do with them? 
    5. How do coronal loops differ from prominences?
    6. A day on Earth is 24 hours. Let’s say you could live on the equator of the Sun. You look up and see Earth in the middle of the sky. How long would it take before the Earth returned to the middle of you sky on the Sun?

Relevant Information and Links

 

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